I have some haemanthus in the ground and when i went to dig them up to add some new soil, i noticed that some bulbs were eaten through the middle and there was a grub inside, but this wasn't the big grubs that you find in the lawns, it was way smaller and had like a black pen dot for an eye. So i placed the ones that were fine in bayer advanced grub control and let them sit in it for awhile, then i planted them all in pots just to be safe, well i was looking through some pots today and there was one little grub eating through some of the roots, and it was small and had a black dot for an eye. So what is this? what am i doing wrong? I used brand new kellogg potting soil and a lot of perlite. I checked the rest of the pots and no grubs, so i am letting the new bulbs sit in the bayer advanced grub control again. And i also watered the remaining pots with the mixture, and then i watered them again just to be safe. so am i doing anything wrong, what can i do to prevent this?